The rotational speed of most steam turbines, particularly single stage steam turbines is controlled by a centrifugal governor coupled or mounted on the end of the drive shaft for the turbine. The governor controls the amount of steam supplied to the turbine to permit operation of the turbine at a desired rotational speed under various load conditions.
As an example of a governor presently in use for a steam turbine, reference is made to a "TG" type governor manufactured and sold by Woodward Governor Company, Fort Collins, Col., and shown in Manual 04042 dated 1984 of Woodward Governor Company. The governor is driven by the drive shaft of the turbine through a flexible coupling. A pilot valve of the governor is responsive to a change in the rotational speed of the turbine and is movable in either a raised upward direction resulting from an increase in rotational speed or a lowered downward direction resulting from a de:crease in rotational speed. If load on the turbine increases which reduces the speed of the turbine, the pilot valve is lowered to effect an increase in the amount of steam supplied to the turbine. If load on the turbine decreases which increases the speed of the turbine, the pilot valve is raised to effect a reduction in the amount of steam supplied to the turbine.
When utilizing steam turbines in refineries, chemical plants, saw mills, and the like, steam temperature and turbine speeds often exceed certain limits and pressurized lubrication is necessary for the beatings of the turbine shaft in order to provide adequate cooling for the bearings. A separate oil pump and motor tier driving the oil pump can be provided for this purpose. However, the utilization of a separate external pump is not preferred. It is preferred to provide an oil pump for supplying pressurized lubrication to the bearings which is driven from the turbine shaft and does not require a separate external motor or other drive means for driving the oil pump.
Heretofore, an oil pump has been coupled to a turbine shaft between the governor and a turbine bearing for supplying pressurized lubrication to the bearings for the turbine. However, the governor and the adjacent bearing housing have been modified to receive the oil pump therebetween. Also, a substantially rigid coupling was provided between the governor shaft and the pump shaft. Thus, the oil pump heretofore was not suitable as a retrofit between a previously existing governor and an adjacent bearing housing.